Method for the production of cellulose esters



Patented Jan. 18, 1938 UNITED STATES PATENT orsics No Drawing.

11 Claims.

This invention relates to a method for the production of cellulose esters.

The method in accordance with this invention is adaptable for the production of various cellulose esters such as, for example, cellulose nitrate,

cellulose acetate, benzyl cellulose, etc. and mixed cellulose esters as, for example, cellulose acetobutyrate land the like.

h In essencethe method in accordance with this invention involves the esterification of a mixture of non-fibrous" and fibrous cellulose. More particularly, the esterification of a mixture of regenerated cellulose and fibrous cellulose is contemplated.

In proceeding for the practical adaptation of this invention, any non-fibrous cellulose may be utilized. Thus, for example, the non-fibrous cellulose may be a cellulose regenerated from a cellulose xanthate or so-called viscose solution,

so from cupro-ammonium solution, a gelatinized cellulose, or the like. Likewise, any suitable fibrous form of cellulose may be utilized as, for example, cotton, cotton linters, wood pulp, or the like.

The esterification of a mixture of non-fibrous and fibrous cellulose may be effected in any desired or known manner, using the usual or desired esterification reagents, apparatus and procedure, for the production of the particular ester desired, as, for example, cellulose nitrate, cellulose acetate, etc.

In practice, the relative proportions of fibrous and non-fibrous cellulose for esterification may be widely varied. By way of example, however, mixtures comprising non-fibrous cellulose in amount, by Weight, within about the range 25%-75% and fibrous cellulose in amount, by weight, within about the range '75%-25% will be found efficient.

In practice the non-fibrous cellulose, as regenerated or gelatinized cellulose, will desirably be in the form of relatively thin, small pieces. Desirably, the regenerated or gelatinized cellulose will be prepared by cutting a film into small pieces, desirably of uniform size. The fibrous cellulose will desirably be in a loose form, though sheeted fibrous cellulose in divided form, or in the form of small pieces, may be used.

As illustrative of practical adaptation of this invention for the production of, by way of ex- .ample, cellulose nitrate, for example, a mixture comprising 50% of regenerated cellulose, as, for example, cellophane, cut up in small, relatively thin pieces and 50% of, for example, cotton linters, is subjected for a period of about 45 min- Application February 8, 1935, Serial No. 5,583

utes, at a temperature of about 44 C. to a nitrating mixture made up on the following formula:

Per cent HNO3 24.05 5 I-INOSOi 4.02

H2SO4 55.68 H2O 16.25

The nitration may be carried out in the usual 7 apparatus used for the nitration of cotton and 10 the subsequent removal of spent nitrating mixture, washing, stabilizing, etc. of the product may follow usual procedure and with use of usual apparatus.

The product will comprise a uniformly nitrated product having a nitrogen content of about 12%.

As will be obvious, products having desired nitrogen content may be produced by variation of the composition of the nitrating mixture, temperature, time, etc., all as is well known to the art. 20

In proceeding for the nitration of mixtures of non-fibrous and fibrous cellulose where the fibrous cellulose comprises wood pulp, the procedure and nitrating mixture outlined above may be used or varied in accordance with practice. 25

In the production of esters other than nitrate, the procedures, reagents and apparatus well known to the art for the production of the various cellulose esters may be followed and used.

The method in accordance with this invention 30 will be found highly advantageous in that a uniformly nitrated product and one productive of excellent clear solutions will be obtained and the difiiculties heretofore met with in the esterification of non-fibrous cellulose, more particularly the difiiculty of handling, especially in nitration, in the usual apparatus will be avoided.

What I claim and desire to protect by Letters Patent is:

l. The method of effecting the uniform ester- 40 ification of non-fibrous cellulose in apparatus and under conditions usually employed for the esterification of fibrous cellulose, which includes admixing 25-'75% of discrete particles of nonfibrous cellulose with -25% of fibrous cellulose and then subjecting the mixture to esterification.

2. The method of efiecting the uniform esterification of regenerated cellulose in apparatus and under conditions usually employed for the esr terification of fibrous cellulose, which includes admixing 25-75% of discrete particles of regenerated cellulose with 75-25% of fibrous cellulose and then subjecting the mixture to esterification.

3. The method of efiecting the uniform esterification of gelatinized cellulose in apparatus and under conditions usually employed for the esterification of fibrous cellulose, which includesadmixing 25-75% of discrete particles of gelat- 4. The method of efiecting the uniform esterification of non-fibrous cellulose in apparatus and under conditions usually employed for the' esterification of fibrous cellulose, which includes admixing 25-75% of discrete particles of non-- fibrous cellulose with 75-25% of cotton fibres and then subjecting the mixture to esterification.

5. The method of effecting the uniform nitration of non-fibrous cellulose in apparatus and under conditions usually employed for the nitration of fibrous cellulose, which includes admixing 25-75% of discrete particles of non-fibrous cellulose with 75-25% of fibrous cellulose and then subjecting the mixture to nitration.

6. The method of effecting the uniform nitration of regenerated cellulose in apparatus and under conditions usually employed for the nitration of fibrous cellulose, which includes admixing 25-75% of discrete particles of regenerated cellulose with 75-25% of fibrous cellulose and then subjecting the mixture to nitration.

7. The method of eifecting the uniform nitration of gelatinized cellulose in apparatus and under conditions usually employed for the nitration of fibrous cellulose, which includes admixing 25-75% of discrete particles of gelatinizedcellulose with 75-25% of fibrous cellulose and then subjecting the mixture to nitration.

8. The method of effecting the uniform nitration of non-fibrous cellulose in apparatus and under conditions usually employed for the nitration of fibrous cellulose, which includes admixing 25-75% of discrete particles of non-fibrous cellulose with 75-25% of cotton fibres and then subjecting the mixture to nitration.

- -9.. The method of effecting the uniform nitration of non-fibrous cellulose in apparatus and under conditions'usually employed for the nitration of fibrous cellulose, which includes admixing 25-75% of discrete particles of non-fibrous cellulose with 75-25% of wood pulp and then subjecting the mixture to nitration.

10. The method of effecting the uniform ester- :ification of non-fibrous cellulose in apparatus :and under conditions usually employed for the esterification of fibrous cellulose, which includes :admixing equal parts of discrete particles of non- :fibrous cellulose and fibrous cellulose and then subjecting the mixture to esterification.

11. The method of effecting the uniform nitration of non-fibrous cellulose in apparatus and under conditions usually employed for the nitration of fibrous cellulose, which includes admixing equal parts of discrete particles of non-fibrous cellulose and fibrous cellulose and then subjecting the mixture to nitration.

' MAHLON G. MILLIKEN. 

